This invention relates generally to the introduction of treatment chemicals to oil and gas wells and, more particularly, to automatic periodic treatment of oil and gas wells by precisely metering and dispersing tretment chemicals into a production fluid flush of the well pumping system.
A variety of corrosive materials are present in the well fluid of producing oil and gas wells. These corrosive materials can cause damage to various metallic components of the wells, including particularly the production tubing. Treatment chemicals are commonly introduced to slow the rate of corrosion and thereby extend the lifetime of the pumping equipment and reduce well downtime.
In addition to corrosion problems, producing wells are sometimes subject to the build-up of paraffin which clogs the well tubing, flow lines and other parts of the well. As with the undesirable corrosion of the pumping equipment, paraffin build-up in the tubing may also be countered by introducing appropriate treatment chemicals. In addition, it may be necessary to introduce other treatment chemicals to selected wells to inhibit or alleviate other problems encountered in day-to-day operation of those wells.
There are several methods presently in use for chemically treating producing oil and gas wells. One method is to continuously pump a very small amount of the treatment chemicals into the well during the well production. The treatment chemical thus falls to the bottom of the well where it mixes with other fluids and is drawn up through the pumping system. This continuous treatment approach, unfortunately, uses unnecessarily large amounts of the treatment chemicals, and is therefore uneconomic and undesirable.
Another current treatment method involves introducing large slugs of the treatment chemicals to the well on a periodic basis, followed by slugs of liquid directly behind the chemical treatment slugs. This approach has been utilized both on a continuous basis in automatic apparatus and on a periodic basis whereby a truck containing the treatment chemicals visits the well from time to time to introduce the chemical treatment slug.
These prior art approaches are, unfortunately, less than ideal since significant amounts of the slug of treatment chemical are coated on the initially encountered well surfaces, limiting the delivery of the treatment chemicals to the lower reaches of the well.